CODEWITHSUNDEEP
androidpollingandroid-runonuithreadandroid-threading
Sandeepa
Sandeepa

Reputation: 3755

Polling in android when only app is not minimized

Lets say I have a method printCount() that print values every second, I want the polling to stop when the android app is minimized. For an example if it was minimized at count = 15 and if I open it after 5 mins, It should resume the polling and print the count from 16. Polling shouldn't run on background when app is minimized.

Upvotes: 0

Views: 377

Answers (1)

Shubham Raitka
Shubham Raitka

Reputation: 1052

This can be achieved in many ways, using Handler, RxJava, Coroutines, etc.

  1. Using RxJava:

    Observable.interval() method, which emits after a particular time interval specified.

    When the app is minimized, onStop() method is called and the observable stops emitting by calling disposable?.dispose(), and starts again in onStart(). I have used global variable for maintaining the count.

    class MainActivity : AppCompatActivity() {

 private lateinit var counterText: TextView
 private var counter: Int = 0
 private var disposable: Disposable? = null

 override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     setContentView(R.layout.activity_main)
     counterText = findViewById(R.id.count)
 }

 override fun onStart() {
     super.onStart()
     disposable = Observable.interval(1000, TimeUnit.MILLISECONDS)
         .subscribeOn(Schedulers.io())
         .observeOn(AndroidSchedulers.mainThread())
         .subscribe { printCount() }
 }

 private fun printCount() {
     counter++
     counterText.text = counter.toString()
 }

 override fun onStop() {
     super.onStop()
     disposable?.dispose()
 }
}

  2. Using Kotlin coroutines:

    class MainActivity : AppCompatActivity() {

  private lateinit var counterText: TextView
  private var counter: Int = 0
  private var job: Job? = null

  override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     setContentView(R.layout.activity_main)
     counterText = findViewById(R.id.count)
  }

  override fun onStart() {
     super.onStart()
     job = CoroutineScope(Job() + Dispatchers.Main).launch {
         while (true) {
            printCount()
            delay(1000)
         }
     }
  }

  private fun printCount() {
     counter++
     counterText.text = counter.toString()
  }

  override fun onStop() {
     super.onStop()
     job?.cancel()
  }
}

Upvotes: 1

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